Jaap

Problem:
The client is trying to implement Redis cache on their website to improve load times but is experiencing issues with comments not being filtered by language in widgets and backend updates. Additionally, switching languages in the Menu-build section sometimes causes the menu to disappear.
Solution:
We recommend setting up and translating your website with WPML before enabling Redis cache to avoid such issues. To resolve the current issues, please add the following code to your theme's functions.php file:

wp_cache_add_non_persistent_groups('comment');

And add this line to your wp-config.php file:

define('WP_REDIS_IGNORED_GROUPS', ['WPML_Cache_Terms_Per_Lang', 'terms', 'nav_menu_relationships']);

This solution might not be relevant if it's outdated or not applicable to your case. We highly recommend checking related known issues at https://wpml.org/known-issues/, verifying the version of the permanent fix, and confirming that you have installed the latest versions of themes and plugins. If the issue persists, please open a new support ticket at WPML support forum.